1. Field of the Invention
The invention relates to an elastomer laminate having an elastic carrier film composed of a thermoplastic elastomer and at least one microtextured cover layer composed of a polymer that has a lower elasticity than the material of the carrier layer. The microtexture has been formed by stretching the laminate beyond the elasticity limit of the cover layer, and elastic recovery of the stretched laminate. The elastomer laminate is used, for example, in disposable hygiene products, and is used, for example, as an elastic waistband or as an elastic closure element on a diaper.
2. The Prior Art
An elastomer laminate having the characteristics described above is described in European Patent No. EP 0 500 590 B1. The cover layer forms a relatively rigid layer that possesses only a little elasticity, and consists, for example, of a polyolefin, particularly polyethylene or polypropylene, a polyethylene terephthalate or polyacrylate. The cover layer of the elastomer laminate has a microtexture that has been produced by stretching the laminate beyond the elasticity limit of the cover layer. The microtexture consists of small wrinkles that form during elastic recovery of the elastomer laminate after stretching, and the orientation of the wrinkles is dependent on the stretching direction. The laminate can be stretched uniaxially transverse to the machine direction, or biaxially. The microtexture is perceived as a roughened, soft surface texture.
A film coextrudate that has an elastomer carrier layer and at least one cover layer composed of a more rigid polymer is described in European Patent Application No. EP 1 316 418 A1. The cover layer consists of a thermoplastic plastic having a brittle consolidated molecular structure that is elongated only slightly when an elongation force is applied, and tears, without any transition, when a predetermined tear force is exceeded. The brittle consolidated molecular structure is irreversibly broken up by uniaxial stretching transverse to the extrusion direction, which is referred to as activation. As a result, the laminate can be elastically elongated transverse to the extrusion direction. The cover layer can consist of a polyolefin that has been made brittle by subsequent treatment, a mixture of polyolefin and polystyrene, or a mixture of polyolefin, polystyrene and ethylene vinyl acetate. In the extrusion direction, which is also referred to as the machine direction, the brittle consolidated molecular structure is maintained and makes the material rigid. The laminate does not have any elasticity in the machine direction.